Speakers are generally divided by the principle of energy conversion into different types including electric (dynamic), electrostatic (capacitive), electromagnetic (reed), or piezoelectric (crystalline) speakers, etc. The last two types are used extensively in rural broadcasting networks, and these speakers are divided by the range of frequency into low-frequency speakers, mid-frequency speakers, and high-frequency speakers and all these speakers are usually installed and combined into a sound box for use.
The speakers may also be divided by the mechanism and structure of energy conversion into dynamic (electric), capacitive (electrostatic), piezoelectric (crystalline or ceramic) electromagnetic (compressed spring), electric ion, or pneumatic speakers, etc., wherein the electric speakers have the advantages of good electroacoustic performance, robust structure, and low cost, and thus provide a wide range of applications. The speakers may also be divided by their acoustic radiating material into paper cone, horn, and diaphragm speakers, wherein the paper cone speakers are divided into circular, elliptic, double-cone, and rubber ring speakers. The speakers may also be divided by the working frequency into bass, midrange, and treble speakers, and some speakers are divided into those designated for answering machines, televisions, and general and high fidelity sound boxes, and some speakers are divided by the impedance of voice coils into low impedance and high impedance speakers, and some speakers are divided by their effect into straight and surrounding sound speakers.
In conventional vehicle speakers, most of these speakers cannot the playing frequency by themselves according to the congestion situation ahead, so that the conventional vehicle speakers provide unsatisfactory warning effect or poor playback performance.
In view of the aforementioned drawbacks of the prior art, the discloser of this disclosure based on years of experience to conduct extensive research and experiment, and finally provided a feasible solution to overcome the drawbacks of the prior art.